1. Field of the Invention
The present invention relates to a coil apparatus for a linear-motor railway system (magnetic levitation railway system).
2. Description of the Related Art
Conventional linear-motor railway systems have employed coil apparatuses of the following schemes in order to propel (P), levitate (L) and guide (G) railway vehicles.
Scheme (1): Propulsion/guide coils each providing propulsion and guide functions are disposed on opposite sidewalls of a guideway, and separate levitation coils are disposed on the bottom surface of the guideway.
Scheme (2): Separately from propulsion coils, levitation/guide coils each providing levitation and guide functions are disposed on opposite sidewalls of a guideway.
Scheme (3): Propulsion/levitation/guide coils each providing propulsion, levitation, and guide functions are disposed on opposite sidewalls of a guideway (hereinafter referred to as a "PLG scheme").
An example arrangement of conventional coil apparatuses will be described.
FIG. 1 is a schematic diagram showing the arrangement of superconductive coils on a vehicle of a conventional linear-motor railway system, as well as the arrangement of ground coils on the ground. FIG. 2 is a schematic diagram showing the arrangement of the superconductive coils on the vehicle of the conventional linear-motor railway system. Here, Scheme (2) is employed, in which, separately from propulsion coils, levitation/guide coils each providing levitation and guide functions are disposed on opposite sidewalls of a guideway.
In these drawings, reference numeral 100 denotes a vehicle of a linear-motor railway system (the length L.sub.1 of the vehicle is 21.6 meters). Reference numeral 101 denotes a bogie for the vehicle (the length L.sub.2 of the bogie is 5.4 meters). Reference numeral 102 denotes superconductive coils disposed on the bogie 101. In this example, four superconductive coils 102 are mounted at a pitch of 1.35 meters such that N-poles and S-poles are formed alternately.
On the ground side, as shown in FIG. 1 three-phase propulsion coils 111 are disposed to form two layers, and levitation/guide coils 112 are disposed at a pitch of 0.45 meter. The propulsion coils 111 and levitation/guide coils 112 form a ground coil 110. Electric power is supplied to the propulsion coils 111 from a triple feeder circuit 120.
In such a conventional scheme, since the propulsion coils 111 are independent of the levitation/guide coils 112, the vehicle can be driven stably, and high reliability is attained in levitation and guide functions.
However, in the above-described conventional scheme as shown in FIG. 1, a large number of propulsion coils 111 and a large number of levitation/guide coils 112 per unit distance must be disposed on the ground. Therefore, the number of man-hour required for installation increases, and the number of connection points also increases, resulting in increased difficulty in inspection and maintenance of the contact points.